$ grep -ir rootdelay /usr/share/initramfs-tools/
/usr/share/initramfs-tools/scripts/local: if [ -z "${ROOTDELAY}" ]; then
/usr/share/initramfs-tools/scripts/local: slumber=${ROOTDELAY}
/usr/share/initramfs-tools/scripts/nfs: if [ -z "${ROOTDELAY}" ]; then
/usr/share/initramfs-tools/scripts/nfs: delay=${ROOTDELAY}
/usr/share/initramfs-tools/scripts/init-premount/udev:# If the rootdelay parameter has been set, we wait a bit for devices
/usr/share/initramfs-tools/scripts/init-premount/udev:if [ "$ROOTDELAY" ]; then
/usr/share/initramfs-tools/scripts/init-premount/udev: /sbin/usplash_write "TIMEOUT $(($ROOTDELAY + 5))"
/usr/share/initramfs-tools/scripts/init-premount/udev: sleep $ROOTDELAY
/usr/share/initramfs-tools/init:export ROOTDELAY=
/usr/share/initramfs-tools/init: rootdelay=*)
/usr/share/initramfs-tools/init: ROOTDELAY="${x#rootdelay=}"
/usr/share/initramfs-tools/init: case ${ROOTDELAY} in
/usr/share/initramfs-tools/init: ROOTDELAY=